1.0 Field of the Invention
The present invention relates generally to a cutting tooth and, more particularly, to a cutting tooth for use in a stump cutting apparatus.
2.0 Related Art
Tree stump cutting devices are well known and widely used and typically include a rotatable, vertical cutting disk and a plurality of cutting bits, or cutting teeth, mounted about the periphery of the disk, with the teeth extending radially beyond the disk periphery. Additional cutting bits may also be mounted on radially inward portions of the disk in a variety of patterns. Known devices typically include cutting bits which are mounted in pairs at any given location, on opposing sides of the disk, by a pair of mount blocks, or pockets, which are separate from the cutting bits. The cutting bits typically include a head portion which includes a carbide cutting tooth and a shank portion, of a generally parallelepiped shape, which is received by a channel having a complementary shape in a corresponding mount block. Typically, a pair of conventional fasteners are inserted through mating holes in a first mount block, the cutting disk, and an opposing mount block with the fasteners conventionally retained. The shank portion of the cutting bits are typically sized so as to extend beyond the channel, transverse to the disk mounting surface, so as to place a generally rectangular surface of the shank portion in abutting relationship with the disk mounting surface. The fasteners are torqued with the resulting frictional forces between the shank and the disk intended to retain the cutting bit within the mount block. The cutting bits are typically made of a hardened steel with the cutting disk made of a relatively softer, more malleable steel. The head portion of the cutting bit may be formed in a generally straight line relationship with the shank, or may be curved and twisted relative to the shank so that the head portion curves away from the cutting disk when installed. Cutting bits and the corresponding, separate mount blocks of the general type just described are disclosed in the following U.S. Pat. No. 3,797,544 to Ver Ploeg, issued Mar. 19, 1974; U.S. Pat. No. 3,935,887 to Van Zante et al, issued Feb. 3, 1976; U.S. Pat. No. 4,759,394 to Clemenson, issued Jul. 26, 1988; U.S. Pat. No. 4,998,574 to Beach et al, issued Mar. 12, 1991; U.S. Pat. No. 5,135,035 to Mills, issued Aug. 4, 1992; U.S. Pat. No. 5,279,345 to LeMaux et al, issued Jan. 18, 1994.
Although cutting bits and mount blocks of the general type disclosed in the foregoing patents have been widely used in the industry, they are subject to one or more of the following problems. The cyclic loading of the cutting bit caused by the carbide tip contacting the stump may cause a failure in the shank portion at the interface with the head portion, due to the relatively small cross-sectional area of the shank portion as compared to that of the head portion at the interface. These cyclic loads, as well as the more infrequent but significantly more severe loads caused by the cutting bit striking a hard object such as a nail or a rock contained within the stump, may cause the shank to twist or rock about the longitudinal axis of the shank so that the relatively hard shank digs into the relatively soft cutting disk so as to leave a permanent impression in the disk. The normal clamp load forcing the shank against the disk may also create a permanent impression in the disk over time, due to the relatively high contact stresses caused by the relatively small contact area of the shank. The twisting or rocking action of the shank within the mount block channel may also cause one or both of the mount bolts to permanently stretch so as to reduce the joint clamp load. Either the permanent depression in the cutting disk, the bolt stretching, or a combination of both may cause the cutting bit shank to become loose within the mount block channel to the extent that the shank is liberated from the channel. This is known to have occurred notwithstanding the use of cutting bit retaining means of the general type illustrated by the shank portion recess 62 and mating pin 84 formed in the cutting bit 10 and half member 14 or 16 of mount block 12, respectively, disclosed in U.S. Pat. No. 4,998,574.
Another problem which has been observed with the general type of cutting bits and mount blocks disclosed in the aforementioned patents is that the distance from the carbide cutting tooth to the mount block surface opposite that which is adjacent the cutting disk, as measured in a direction substantially transverse to the disk lateral surface, is insufficient to allow uncut material such as small rocks, as well as cut debris to freely pass rearward by the mount block. Consequently, the uncut material and cut debris has been known to abrade the outer surface of the mount block, as well as the bolt heads inserted into the mount blocks. After a period of operation of the stump cutting device, several of the mount blocks and associated bolt heads may be abraded in this manner. Subsequently, one or more mount blocks may be replaced due to excessive abrasion. The new, replacement mount blocks may be significantly heavier than the remaining, abraded mount blocks on the cutting wheel of the stump cutting device. The increased mass of the new, replacement mount blocks has been known to create vibration problems with existing stump cutting devices.
Yet another problem with known cutting tips and mount blocks is proper alignment of the cutting tip shank within the corresponding mount block channel, so as to position the cutting tip at the desired radial location on the cutting wheel of the stump cutting device. This alignment procedure is relatively time consuming and therefore costly, and is subject to error.
In view of the foregoing deficiencies associated with known cutting bits and the associated and separate mounting blocks, applicant's invention is herein presented.